Devices for pre-tensioning a seatbelt prior to a vehicle collision have been in existence for many years and under constant development. The tensioning of the seatbelt prior to the sensing of vehicle impact and prior to the pre-tensioning that occurs just before vehicle impact is a more recent development in seatbelt tensioning and is known in the art as “pre-pretensioning”. These systems employ a motorized pre-pretensioning retractor that is activated during pre-impact situations and/or in non-impact situations when the sensing system initiates a vehicle pre-impact signal.
Early tensioning of the seatbelt can improve occupant kinematics during a vehicle collision and help reduce or prevent injury to an occupant. Another advantage of pre-crash/impact tensioning of the seatbelt is the tactile feedback that a driver receives from the seatbelt that warns the driver to take action. Pre-pretensioning devices are reversible allowing for early activation prior to impact and in cases where impact does not occur, the system returns to a normal tensioning level.
U.S. Pat. No. 6,616,186 issued to NSK Autoliv discloses systems and methods for undertaking pre-pretensioning and is hereby incorporated by reference. Further, U.S. Pat. No. 6,616,186 discloses systems having multiple belt tensioning devices and a motor driven retractor and is hereby incorporated by reference.
While current pre-pretensioning devices and methods for pre-pretensioning a vehicle seatbelt achieve their intended purpose, many enhancements and additional features are needed. Therefore, a new and improved pre-pretensioning system and method would be desirable.